1. Field of the Invention
This invention relates to computer systems employing modems and more particularly to power supply circuits for modems.
2. Description of the Related Art
An ongoing developmental goal of manufacturers has been to reduce the power consumption of computer systems. Reducing power consumption typically reduces heat generation of the system, thereby increasing reliability and decreasing costs. Reducing power consumption has been particularly important in maximizing the operating life of battery powered portable computer systems. Battery powered portable computer systems include personal information devices ("PIDs"), hand held personal computers ("HPC"), digital assistants and smart phones.
Battery powered portable computer systems have limited use before requiring recharge or replacement of the batteries. In most cases, add-on devices, such as modems, create an additional power drain on the limited power available from the batteries. Often times, the batteries cannot provide enough power for both the portable computer system and an add-on device. Alternatively, if the batteries can provide enough power for both the computer system and add on device, the life of the battery (prior to recharge or replacement) is severely limited. In some cases, with relatively high-power add-on devices, such as a V.34 modem, the battery life is so limited that use of the add-on device is impracticable.
What is desired is an alternative power source for providing power to add-on devices and/or computer systems.